Gas turbine engines operate to produce mechanical work or thrust. Specifically, land-based gas turbine engines typically have a generator coupled thereto for the purposes of generating electricity. The shaft of the gas turbine engine is coupled to the generator. Mechanical energy of the shaft is used to drive a generator to supply electricity to at least a power grid. The generator is in communication with one or more elements of a power grid through a main breaker. When the main breaker is closed, electrical current can flow from the generator to the power grid when there is a demand for the electricity. The drawing of electrical current from the generator causes a load to be applied to the gas turbine. This load is essentially a resistance applied to the generator that the gas turbine must overcome to maintain an electrical output of the generator.
Increasingly, a control system is used to regulate the operation of the gas turbine engine. In operation, the control system receives a plurality of indications that communicate the current operating conditions of the gas turbine engine including pressures, temperatures, fuel flow rates, and engine frequencies. In response, the control system makes adjustments to the inputs of the gas turbine engine, thereby changing performance of the gas turbine engine based on the plurality of indications in light of look-up tables coded into the memory of the control system. Over time, this performance may fall outside a preferred operating range due to mechanical degradation of the gas turbine engine or changes in operational conditions such as ambient temperature or inlet fuel properties (e.g., temperature, pressure, and composition). For instance, the gas turbine engine may begin operating in a state where combustion of the inlet fuel causes unwanted operational dynamics, such as instability or diminished durability. By way of example, unrevealed to the gas turbine engine, the composition of the inlet fuel may have degraded to include a greater number of hydrocarbons, which exhibit a lower heating value per unit volume. Or, in another example, the inlet fuel temperature may have unexpectedly increased, where heated inlet fuel exhibits a lower heating value per unit volume.
Upon recognizing this state of reduced energy release, the control system may conventionally attempt to implement corrective measures, such as increasing a flow rate through fuel nozzles, which introduce the inlet fuel to the combustors, in order to achieve the previous level of energy release. Because these corrective measures do not directly address the issue of changed inlet fuel properties (e.g., degraded fuel composition and increased fuel temperature), blindly compensating by an increased flow rate may provoke combustion instability within the gas turbine engine, which further impairs the operational dynamics (e.g., stability and durability) thereof.
Often, manual tunings may be performed to update the control system such that it recognizes the change in fuel properties. However, manual tuning is labor intensive and can create business-related inefficiencies. For instance, manual tuning for fuel properties may involve utilizing a gas chromatograph to measure a quality (i.e., composition) of the inlet fuel via in-line, gas analysis. Extracting an accurate measurement (e.g., heating value of the inlet fuel) from the gas chromatograph generally requires a considerable amount of time. Further, because an elaborate process is required to ascertain the heating value of an inlet fuel, other conventional tools exhibit the same short-comings (e.g., ability to accurately measure fuel composition on-the-fly) as the gas chromatograph, a more robust model of detecting changes to fuel properties and for alerting the control system of the detected changes is addressed by embodiments of the present invention.